P5W-DH-Deluxe how to get 3gb memory to be used in 32bit XP Pro ?

Discussion in 'Asus' started by It's Not Me, Feb 27, 2007.

  1. It's Not Me

    It's Not Me Guest

    I show in bios 3072mb ram, and memtest show the full gb also. I boot
    into windows XP pro sp2 with all latest updates using auto-patcher. In
    windows it only show 2gb memory. I read about the 4gb limitation but I
    am only trying to get 3gb working. It shows Physical Address Extension
    in system properties as I read somewhere this has something to do with
    over 2gb memory usage in windows. I have re-installed windows to no
    avail. I tried Xp Pro x64 edition, and it shows all 3gb memory. I
    don't want to use 64 bit though as none of my software is 64 bit and
    some even will not run in 64 bit Xp.

    I have a DFi infinity 975g/x which is also the Intel 975 chipset with
    3gb of 2x512 2x1204 of OCZ pc5400 memory, and it works perfectly sees
    the memory just fine in XP.. So what gives?????
     
    It's Not Me, Feb 27, 2007
    #1
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  2. It's Not Me

    Bill Jemison Guest

    I posted a similiar question on 2/17 with the subject > Why less than 3
    GB RAM recommendation in A8N31-SLI deluxe

    Read all the posts but in nutshell it is a software (Windows XP 32 bit
    doesn't recognize all the available RAM) issue not a hardware issue.
     
    Bill Jemison, Feb 27, 2007
    #2
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  3. Yet my P5P800 shows all of my 3 GB of RAM under XP Pro. It originally
    had 1 GB and I later added another 2 GB of RAM.
     
    Michael W. Ryder, Feb 27, 2007
    #3
  4. It's Not Me

    tcsenter Guest


    The memory addressing needs of your particular hardware configuration
    are greater than 1GB, which is not unusual in full-featured
    contemporary motherboards with lots of bells and whistles. The total
    range of this memory space required by your hardware to function is
    often referred to as the PCI memory hole.

    Three or four years ago, the typical PCI memory hole was 512MB ~
    768MB. Today, its much larger on all but the most basic motherboards
    using entry-level chipsets with no discrete controller chips for mass
    storage, firewire, and the like. Your Intel ICH/MCH/FMW alone
    requires 768MB out of the gate according to Intel white papers, not
    including a graphics card or any other discrete PCI devices.

    Windows doesn't decide how much memory gets reserved for your
    hardware. The BIOS does based on the enumerated memory space
    requirements of your hardware, the chipset design, the BIOS writer's
    design choices, and industry standards (e.g. PCI Spec), then
    communicates to Windows what memory is available to it.

    As for physical address extensions (PAE), Microsoft changed the
    behavior of PAE kernel mode in Windows XP starting with Service Pack
    2. Support for more than 4GB of physical memory via 36-bit PAE was
    effectively disabled, because 36-bit PAE exposed a class of driver
    bugs that were too widespread to let 36-bit PAE go 'into the wild' on
    desktop operating systems, which need to work with the broadest range
    of hardware available including older hardware that isn't even
    supported anymore. 36-bit PAE is still available on Microsoft's 32-
    bit server or enterprise operating systems (e.g. Windows Server 2003
    Enterprise and Windows 2000 Advanced Server).

    So PAE will not do anything for your PCI memory hole issue on Windows
    XP unless it is pre-SP2. Even then, it doesn't reclaim all of it, but
    you get some memory space back, at the significant risk of driver bugs
    and other problems.

    Lastly, if you have an option in BIOS for S/W or H/W memory remapping,
    it is of no use on Windows XP SP2, and can actually increase the PCI
    memory hole size that you otherwise would have. Disable it unless
    your operating system supports more than 4GB RAM via 64-bit OS or 36-
    bit PAE.

    Regards,

    Tim
     
    tcsenter, Feb 27, 2007
    #4
  5. It's Not Me

    It's Not Me Guest

    It must be something with the bios on the P5W as my asus commando is
    currently running just fine with XP Pro and 2x512 2x1024 of pc6400
    corsair. The commando is a different chipset ( P965 ) how ever the DFI
    board was a 975 chipset and it to could get Xp to see all 3gb ram.

    Oh well back too asus web site and further googling for a true
    solution. Thanks for responding.
     
    It's Not Me, Feb 27, 2007
    #5
  6. It's Not Me

    It's Not Me Guest

    Same here with my asus commando board and DFI Infinity both upgraded
    to 3gb memory and windows sees it just fine. A side note the commando
    does show slightly less than 3gb it shows as 2.93gb memory.
    Well back to beating my head on the desk...........
     
    It's Not Me, Feb 27, 2007
    #6
  7. It's Not Me

    It's Not Me Guest

    Thanks for the tip Tim I will put my gutted P5W back together again
    and look for those options in bios.
     
    It's Not Me, Feb 27, 2007
    #7
  8. It's Not Me

    steve Guest

    steve, Mar 3, 2007
    #8
  9. It's Not Me

    John Guest

    try adding this switch to boot.ini /3GB
     
    John, Mar 3, 2007
    #9
  10. It's Not Me

    tcsenter Guest


    The /3GB switch has nothing to do with making a 32-bit operating
    system use all 4GB of RAM or somehow increase the physical address
    space of 32-bit operating systems. This switch only changes the
    balance between kernel mode and user mode virtual address space that
    an application process can have.

    Normally, every application can have up to 2GB of kernel mode virtual
    address space and 2GB user mode virtual address space at its disposal
    (4GB total). Using the /3GB switch changes this balance by increasing
    user mode limit to 3GB while DECREASING kernel mode to 1GB (still just
    4GB total).

    Only applications that explicitly request this using
    'LARGEADDRESSAWARE' flag can utilize the 3GB user mode virtual address
    space, which currently is limited primarily to server and enterprise
    class applications.


    Regards,

    Tim
     
    tcsenter, Mar 12, 2007
    #10
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